1. Field of the Invention
The present invention relates to apparatus for chemical analysis, especially, for chemical analysis to measure properties, concentration, and others of dissolved constituents in fluid.
2. Prior Art
As for an example of conventional apparatus for chemical analysis, an apparatus for chemical analysis having an analytical path to analyze silver nitrate is known. Operation of the apparatus is explained briefly hereinafter.
First, a sampling valve (a) is activated to supply a sample including NO.sub.3 into carrier liquid in a mixing tube (b) in a manner like a sandwich. Next, a pump (c) is activated to flow the sample into the mixing tube (b) for mixing and diluting the sample with the carrier liquid to a designated concentration. A necessary period for flowing the sample to a sampling valve (d) is previously calculated based on velocity of the carrier liquid, and after a predetermined elapsed time, the sampling valve (d) is activated to supply a part of the diluted sample into carrier fluid in another mixing tube (e) for diluting the diluted sample again to a far diluted condition. Next, a reducing column reduces NO.sub.3 in the diluted sample to NO.sub.2. At an injection portion, a coloration reagent for NO.sub.2 is added to the reduced sample and mixed with a mixing tube (g) to react sufficiently, and then, a colorimetric quantitative analysis is performed with light having a designated wave length.
In other examples of analytical apparatus, an analytical apparatus is composed of a path suitable for analyzing silic acid coexisting with phosphoric acid. First, a coloration reagent 1 is added to a sample with carrier liquid, and coloring reactions for both phosphoric acid and silic acid are caused in a successive mixing tube (h). Subsequently, a pump (i) is activated to add a reagent for diminishing the coloration of the phosphoric acid to the sample, after passing through a mixing tube (j), a colorimetric quantitative analysis for silic acid is performed using an absorptiometric flow cell (k).
As for an example of other prior art, a continuous flow analytical method has been disclosed in JP-A-61-42211 (1986). An apparatus for the above method forms reaction paths by combining a several liquid elements which are formed of mixing path blocks having a designated length. When changing an analytical object, the number of the blocks can be varied, other reaction path can be connected to an intermediate portion of the reaction path, and other variation can be applied for forming optimum mixing and reaction paths suitable for the method of above chemical analysis. Operation of the apparatus is the same as the operation of the above described two prior art.
An example of manufacturing the above apparatus for chemical analysis using microprocessing has been disclosed in a reference (Elizabeth Verpoorte et al "A Three-Dimensional Micro Flow System for a Multi-step Chemical Analysis" Proc. of The 7th International Conference of Solid-State Sensors and Actuators). In the above reference, a method for manufacturing small size analytical apparatus for chemical analysis of phosphoric acid concentration by combining two silicon substrates whereon fine mixing paths and a micropump are formed respectively by photolithography is disclosed. Operation of the analytical apparatus is the same as the operation in the above prior art.
As the above two examples reveal, each of chemical analysis for nitric acid and phosphoric acid requires quite different flow paths composition each other. Furthermore, JP-A-61-42211 (1986) disclosed a same example as the above examples. Generally speaking, when an object of chemical analysis differs, composition such as flow paths, columns, and flow cell must be rearranged in accordance with the object. Therefore, apparatus based on prior art requires a large amount of man-hours for changing connection, and hence, it is impossible to analyze many kinds of samples in a short time. Even if the connection changing has been completed, it is necessary further to settle flow conditions such as merging timing of a sample and a reagent, and a flow rate of carrier liquid, and measuring conditions of a detector, and other conditions precisely for each analytical items. Therefore, significantly high grade special knowledge is required.
In data processing after collecting measuring data, the processing methods differ each other significantly depending on kinds of analytical objects. Accordingly, repeated settlements of processing condition corresponding to analytical objects were required, and there has been a defect such as inconvenience.
Recently, demands for chemical analysis apparatus are expanding from a purpose for research in spots to industrial uses such as quality control in medical manufacturers and food industries, and accordingly, an usage wherein a large amount of samples are analyzed fast is becoming major. On the other hand, a measuring objective range of chemical analysis is expanding rapidly as represented by increasing items of water quality analysis. As a result, demands for multipurpose type analytical apparatus which performs various kinds of analysis by only one apparatus have been increased. A trial to overcome the inconvenience of prior art described in the above references by reducing size of the apparatus itself has been continuing, but, an appropriate apparatus which makes it possible to analyze multi-items concurrently has not been proposed yet.